Thesis (M.A. (Botany)) --University of Limpopo, 2012 / Several South African Euphorbia species are threatened with extinction, yet only a few have been studied in sufficient detail to develop a conservation management plan based on sound scientific principles. The focus of this study was on one of the highly threatened dwarf Euphorbias, namely Euphorbia groenewaldii. Apart from a report on the species distribution and estimated population numbers by Raal (1986), virtually nothing is known about this attractive succulent species. Conservation and management of threatened species requires a thorough understanding of their biology, ecological requirements and spatial distribution which should form the basis of a monitoring programme that must be conducted at regular intervals. Euphorbia groenewaldii is endemic to six rocky schist and quartzite ridges in the vicinity of Polokwane, the capital of South Africa’s Limpopo Province. The species’ small global range, small number of populations and small population sizes in some instances, render the species susceptible to anthropogenic and environmental stochasticity. Biotic and abiotic features were investigated to determine their influences, as well as, the threats (trampling, anthills, herbivory and number of senescent plants) facing Euphorbia groenewaldii. Canopy area was used to determine the stage (age) and size structure of each population. Biotic features and natural environmental components considered were percentage cover of grass, forbs, dead vegetation, stones, fixed rock and bare ground. The percentage cover, of all the biotic features (grass, forbs and dead material) and environmental components (stones, fixed rock and bare ground), most preferred by E. groenewaldii is close to 25% in the direct vicinity of the individual plant. Euphorbia groenewaldii select areas with fixed rock more than in any other biotic feature or environmental component. This could be for protection from, or a result of, trampling by large herbivores, or that it’s most preferred mineral substance is found within this geology. Abiotic features considered in this study were; fire, aspect, slope degree, slope position and soil. The E. groenewaldii population as a whole prefers to grow on the northern aspects. Furthermore, with threats affecting all the populations, it is forced to grow in the middle of steeper slopes. Currently the only fire ‘regime’ is a natural or accidental occurring fire. The area where E. groenewaldii grows belongs to the local government and is open to public traffic. If a regular (once a year) cold-fire regime for E. groenewaldii can be put in place and, if possible, coincide with rainfall events it could help the release of more seeds and help with a more constant rate of seedling recruitment for this species. Such a fire event was witnessed during the study period and subsequent new growth and seedling appearances were recorded. Threats that were noted and considered were mostly of a biotic nature (absence of fire being the exception) and included trampling, herbivory and termite mounds. Other threats not included are urban expansion and mining/quarrying activities. These types of threats are real and more extensive, and if not monitored could completely destroy a population in a very short time period. Trampling is a significant threat facing this species, particularly at the Melkboomfontein population, where 31% of the population shows physical signs of trampling by livestock; mainly cattle. Herbivory is also a threat to E. groenewaldii and causes significant damage (15% over the total population according to the statistical analysis). There is also a significant difference in the effect anthills have on E. groenewaldii as opposed to the other threats, which have almost no effect on its population size. In addition to the above, surveys were conducted to determine the species’ present extent of occurrence and area of occupancy to obtain population size estimates and densities. The results were compared with data of a study by Raal in 1986. The results of this study showed a dramatic decline in population numbers. Possible reasons for the reduction include habitat loss, better survey techniques (that provided better predictions of population density) and a more comprehensive survey and data analysis in this study, and a failure to implement the conservation management plan proposed by Raal (1986). It is estimated that the total number of individuals in all the populations comprise approximately 26 500 individual plants, with all occurring in an area of less than 4 km2 (excluding the Dalmada populations). The small extent of occurrence suggests that E. groenewaldii populations require urgent protection. An investigation of morphological differences between E. groenewaldii and E. tortirama was conducted. This investigation attempted to find external morphological differences by looking at the flower peduncles, colour of bracts and spine shields. Analysis of these data showed differences in the length of the peduncles (longer in E. groenewaldii than in E. tortirama); colour of bracts (colourless in E. groenewaldii as opposed to the reddish-pink bracts of E. tortirama) and the continuation (E. groenewaldii) and non-continuation (E. tortirama) of spine shields. In 1986, Euphorbia groenewaldii’s conservation status was considered endangered; it is still the case today. However, the IUCN status of E. groenewaldii was reevaluated on the current data gathered, which has placed E. groenewaldii in the Critically Endangered category. This is mainly due to the small extent of occurrence (approximately 4 km2) of the species (less than the 100 km2 which according to the IUCN Redlist Categories and Criteria, 2006, criteria B, classifies species as critically endangered).

Thesis (M. Sc. (Botany)) -- University of Limpopo, 2016 / The need to conduct a detailed biological and ecological study on Euphorbia clivicola was sparked by the drastic decline in the sizes of the Percy Fyfe Nature Reserve (Mokopane) and Radar Hill (Polokwane) populations, coupled with the discovery of two new populations; one in Dikgale and another in Makgeng village. The two newly (2012) discovered populations lacked scientific data necessary to develop an adaptive management plan. This study aimed to conduct a detailed biological and ecological assessment, in order to develop an informed management and monitoring plan for the four populations of E. clivicola. This study entailed a demographic investigation of all populations and an inter-population genetic diversity comparison so as to establish the relationship between all populations of E. clivicola. The abiotic and biotic interactions of E. clivicola were examined to determine the intrinsic and extrinsic factors causing the decline in the Percy Fyfe Nature Reserve and Radar Hill population sizes. Fire as one of the abiotic factors was observed to be beneficial to E. clivicola because it weakened their number one competitor, i.e., graminoids in populations with low or no grazing pressure. Fire also destroys refuge for rodents, which feed on the flowers of E. clivicola, as such, affecting reproduction success. An exponential growth was observed to be directly proportional to fire damage. The populations of Percy Fyfe Nature Reserve, Radar Hill, and Dikgale were found to be genetically compatible. The genetic homogeneity makes intra-population restocking possible. Anthropogenic induced fragmentation proved to be detrimental to Radar Hill and Makgeng populations of E. clivicola, by reducing the Area of Occupancy of the species and hindering seed dispersal. Propagules of E. clivicola are dispersed down a gradient by surface water run-off, and therefore; slope angle and aspect directs the expansion of the E. clivicola populations. Euphorbia clivicola plants (71%) were observed to prefer north-facing gentle slopes of < 11°. Grass cover of > 60% negatively affects the reproduction success of E. clivicola by obstructing pollinators’ access to flowers. DNA data from this study indicate that the Percy Fyfe Nature Reserve population can be re-stocked with genetically attuned individuals from Radar Hill and Dikgale populations of E. clivicola at suitable habitats to prevent extinction. The exclusion of herbivores from the Radar Hill population triggered a negative domino effect (increased grass cover, refuge for herbivores, and amplified the density between individuals), as such alternative management actions need to be adopted for the population of Percy Fyfe Nature Reserve. In order to halt the dramatic decline at Radar Hill population, an adaptive management plan that possesses three main focal points, which are; objectives, management, and monitoring is proposed. The population of Percy Fyfe Nature Reserve is so drastically reduced that it requires a more intensive approach; hence, a recovery plan is proposed. This plan takes into account the genetic similarity of three populations (Percy Fyfe Nature Reserve, Radar Hill and Dikgale), and model management and monitoring objectives to be more or less similar, so as to save time and resources. The three common components of monitoring the above mentioned populations are population size, canopy size, and density.

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Thesis (M.Sc.(Anatomy))--University of Pretoria, 2009. / Includes bibliographical references.

Thesis (M.S. - Plant Sciences)--University of Arizona, 1984. / Includes bibliographical references (leaves 47-51).

El objetivo de esta tesis fue estudiar tres especies vegetales empleadas por la medicina tradicional: Euphorbia serpens, E. schickendantzii y E. collina, para evaluar la presencia de actividad, diurética, antiparasitaria, citotóxica y antimicrobiana, e identificar y aislar el/los principio/s activo/s. Del material vegetal desecado se realizaron extracciones seriadas con solventes de polaridad creciente, hexano, acetato de etilo y metanol, obteniéndose extractos hexánicos, de acetato de etilo y metanólicos respectivamente. Además, a partir del material desecado se obtuvieron extractos hidroalcólicos por maceración y extractos acuosos por infusión. En el Capítulo 1 se evaluó la actividad diurética de E. serpens, debido a su uso como diurética en la medicina tradicional. Utilizando modelos in vivo se ensayaron los extractos hexánico, metanólico y de acetato de etilo de E. serpens, y acuosos e hidroalcólicos de las tres especies vegetales estudiadas. No se encontró actividad diurética, para ninguna de las plantas. En el Capítulo 2 se evaluó la actividad antihelmíntica de las tres especies vegetales, exponiendo larvas de Ancylostoma caninum a extractos hexánicos, de acetato de etilo y metanólicos; y huevos de Haemonchus contortus a extractos hidroalcólicos. Los extractos metanólicos obtenidos de las tres especies tuvieron efecto inhibitorio sobre la motilidad larval. El extracto metanólico de E. collina, además, inhibió la eclosión de huevos. Los ensayos confirmaron el efecto antihelmíntico de E. collina. En el Capítulo 3 se evaluó la actividad citotóxica de las tres especies de Euphorbia utilizando el test de letalidad de Artemia salina, exponiendo larvas a diferentes concentraciones de extractos hexánicos, de acetato de etilo y metanólicos. Todos los extractos mostraron actividad citotóxica al menos en una de las dosis empleadas. El extracto hexánico de E. collina fue el que presentó la mayor actividad. Además, se realizaron ensayos de toxicidad in vivo de extractos metanólico, hidroalcohólico y hexánico de E. collina, los cuales no mostraron toxicidad en ratones. En el Capítulo 4 se evaluó la actividad antimicrobiana de los extractos hexánicos, de acetato de etilo y metanólicos de E. serpens, E. schickendantzii y E. collina, contra Escherichia coli, Pseudomona aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis y Fusarium verticillioides, en métodos in vitro. Se determinó que los extractos de acetato de etilo y metanólico de E. collina, y metanólico de E. schickendantzii, tuvieron actividad antimicrobiana. Los extractos hexánico y de acetato de etilo de E. collina crudos, se reunieron y se fraccionaron mediante una cromatografía en columna. De las fracciones obtenidas, una de ellas, denominada G10-11 inhibió el 50 % del crecimiento de Fusarium verticillioides. En el Capítulo 5 se realizó una marcha fitoquímica con extractos etanólicos de E. serpens, E. schickendantzii y E. collina, determinando la presencia de compuestos esteroidales, triterpenos, flavonoides, taninos, fenoles, saponinas, lípidos, proteínas e hidratos de carbono. De la fracción G10-11 se aisló una mezcla de 51 % de cicloartenol y un 49 % de 24-metilenocicloartenol. / The aim of this work was to study three species used by traditional medicine: E. serpens, E. schickendantzii and E. collina, to evaluate the presence of diuretic, antiparasitic, cytotoxic and antimicrobial activity; identify and isolate their active principles. Sequential extractions were carried out on dry plant with solvents of growing polarity, hexane, ethyl acetate and methanol, obtaining hexane, ethyl acetate and methanolic extracts, respectively. Also, hydroalcoholic extracts by maceration and aqueous extracts by infusion from the dry material were obtained. In Chapter 1, the diuretic activity of E. serpens was evaluated due to its use as a diuretic in traditional medicine. Using in vivo models, the hexane, methanlic and ethyl acetate extracts of E. serpens and aqueous and hydroalcoholic extracts of the three species were tested. No diuretic activity was found for any of the plants. In Chapter 2, the anthelmintic activity of the three plant species was evaluated, exposing Ancylostoma caninum larvae to hexanic, ethyl acetate and methanolic extracts; and Haemonchus contortus eggs to hydroalcoholic extracts. The methanolic extracts obtained from the three species had an inhibitory effect on larval motility. The methanolic extract of E. collina also inhibited the hatching of eggs. The tests confirmed the anthelmintic effect of E. collina. In Chapter 3, the cytotoxic activity of the three Euphorbia species was evaluated using the Artemia salina lethality test, exposing larvae to different concentrations of hexane, ethyl acetate and methanolic extracts. All the extracts showed cytotoxic activity at least in one of the doses used. The hexane extract of E. collina was the one that presented the highest activity. In addition, in vivo toxicity tests of methanolic, hydroalcoholic and hexanic extracts of E. collina were carried out, which did not show toxicity in mice. In Chapter 4, the in vitro antimicrobial activity of the hexane, ethyl acetate and methanolic extracts of E. serpens, E. schickendantzii and E. collina was evaluated against Escherichia coli, Pseudomona aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis and Fusarium verticillioides. It was determined that the ethyl acetate and methanolic extracts from E. collina, and methanolic extracts from E. schickendantzii, had antimicrobial activity. The crude E. collina hexane and ethyl acetate extracts were combined and fractionated by column chromatography. Of the fractions obtained, one of them, called G10-11, inhibited 50 % of the growth of Fusarium verticillioides. In Chapter 5 a phytochemical screening was carried out with ethanolic extracts of E. serpens, E. schickendantzii and E. collina, determining the presence of steroidal compounds, triterpenes, flavonoids, tannins, phenols, saponins, lipids, proteins and carbohydrates. In the fraction G10-11, a mixture of 51 % cycloartenol and 49 % 24-methylenecycloartenol was isolated.

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-06-20T18:12:54Z No. of bitstreams: 1 texto completo.pdf: 1756399 bytes, checksum: 4cd93ccd34ab97ff3909ee83598fa241 (MD5) / Made available in DSpace on 2017-06-20T18:12:54Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1756399 bytes, checksum: 4cd93ccd34ab97ff3909ee83598fa241 (MD5) Previous issue date: 2016-02-25 / A maioria dos begomovírus monossegmenados do Velho Mundo (família Geminiviridae) estão associados a DNAs satélites, classificados como alfa- e betassatélites. Os alfassatélites são capazes de replicar-se de forma autônoma, mas dependem do vírus auxiliar para o movimento, encapsidação e transmissão pelo inseto vetor (Bemisia tabaci). Recentemente, o Euphorbia yellow mosaic alphasatellite (EuYMA) foi encontrado em associação com o begomovírus Euphorbia yellow mosaic virus (EuYMV), infectando plantas de Euphorbia heterophylla no Brasil. Compreender a dinâmica da interação entre begomovírus e DNAs satélite em plantas não cultivadas, tais como E. heterophylla, é importante porque eles podem ser transferidos para plantas cultivadas, dado o hábito polífago de B. tabaci. Este estudo teve como objetivos: (i) analisar as diferenças fenotípicas da infecção pelo EuYMV na presença e na ausência do EuYMA; (ii) avaliar se a proteína alfa-Rep do EuYMA possui atividade supressora de silenciamento de RNA; (iii) comparar a transmissão do EuYMV por B. tabaci MEAM1, na ausência e na presença do EuYMA. Foram coletadas amostras (n=165) de E. heterophylla em diversos estados do Brasil. Clones infecciosos foram gerados para realizar-se a caracterização biológica e inoculação das plantas. EuYMV foi detectado em 126 amostras e EuYMA foi detectado em apenas seis amostras. Isoladamente, o EuYMV causa clorose internerval e mosaico amarelo. Em associação com o EuYMA, os sintomas são mais severos, caracterizados por mosaico amarelo muito mais intenso, encarquilhamento foliar e redução do crescimento. O DNA-A do EuYMV pode infectar E. heterophylla na ausência do DNA-B, provocando ou não um mosaico amarelo atenuado. A sequência codificadora completa do gene alfa-Rep do EuYMA foi clonada em vetor binário e transformada em células de Agrobacterium tumefaciens. Um ensaio de supressão de silenciamento de RNA foi realizado com esta construção em plantas de Nicotiana benthamiana. Os resultados indicam que a proteína alfa-Rep do EuYMA não atua como supressora de silenciamento de RNA. Foi realizado um ensaio de transmissão do EuYMV por B. tabaci, na presença e ausência de EuYMA, em duas repetições biológicas. Vinte plantas foram utilizadas para cada tratamento. Isoladamente, o EuYMV foi transmitido para 17 e 18 plantas na primeira e segunda repetição, respectivamente. Em associação com EuYMA, o vírus foi transmitido para 15 e 14 plantas na primeira e segunda repetição, respectivamente, uma diferença estatisticamente significativa. Assim, os resultados indicam que o EuYMA afeta negativamente a transmissão do EuYMV pelo vetor, consequentemente afetando a disseminação do vírus no campo. / The majority of Old World monopartite begomoviruses (family Geminiviridae) are associated with satellite DNAs, classified as alpha- and betasatellites. Alphasatellites are capable of autonomous replication, but depend on the helper virus for movement, encapsidation and transmission by the insect vector (Bemisia tabaci). Recently, Euphorbia yellow mosaic alphasattelite (EuYMA) was found in association with Euphorbia yellow mosaic virus (EuYMV), infecting Euphorbia heterophylla plants in Brazil. Understanding the dynamics of the interaction between begomoviruses and satellite DNAs in non-cultivated plants, such as E. heterophylla, is important as they can be transferred to cultivated plants, given the polyphagous habit of B. tabaci. The objectives of this study were: (i) to analyze phenotypic differences of EuYMV infection in the presence and absence of EuYMA; (ii) to evaluate whether the alpha-Rep protein of EuYMA possesses RNA silencing suppressor activity; (iii) to compare the transmission of EuYMV by B. tabaci MEAM1 in the absence and presence of EuYMA. Samples (n=165) of E. heterophylla were collected in several states of Brazil. Infectious clones were generated to perform the biological characterization and inoculation. EuYMV was detected in 126 samples and EuYMA was detected only in six samples,. Alone, EuYMV causes interveinal chlorosis and yellow mosaic. In combination with EuYMA, the symptoms are more severe, characterized by a more intense yellow mosaic, leaf shriveling and stunting. The DNA-A of EuYMV can infect E. heterophylla in the absence of the DNA-B, causing attenuated yellow mosaic or no symptoms at all. The complete coding sequence of the alpha-Rep gene of EuYMA was cloned in a binary vector and transformed in Agrobacterium tumefaciens. An RNA silencing supression assay was performed with this construct in Nicotiana benthamiana plants. The results indicate that the alpha-Rep protein of EuYMA does not act as an RNA silencing suppressor. A transmission assay of EuYMV by B. tabaci, in the presence and absence of EuYMA, was performed in two biological replications. Twenty plants were used for each treatment. Alone, EuYMV was transmitted to 17 and 18 plants, in the first and second replication respectively. In association with EuYMA, the virus was transmitted to 15 and 14 plants, in the first and second replication respectively, a difference which was statistically significant. Thus, our results indicate that EuYMA negatively affects the transmission of EuYMV by the vector, consequently affecting the spread of the virus in the field.